Union Switch and Signal (now part of AnsaldoSTS) published a corporate history in 2011. (US&S, of course, was the signalling company established by George Westinghouse and was one of the big two US signalling contractors. It became a major player in the UK, apparently owning 1/3 of Westinghouse.)

The details are: Safety on the Rails, Joanne L. Harris, Ansaldo STS USA, 2011. 185pp, a little larger than A4. It doesn't appear to have an ISBN. The list price seems to be about $40US.

I haven't had a chance to read the book yet. A quick glance suggests that production values are typical of corporate history - nicely laid out with a fair number of pictures, including a lovely colour picture of a Hall banjo signal.

Note that this is not the same book as the previous US&S book "The Search for Safety" (Mary Brignano & Hax McCullough, 1981).